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| United States Patent |
5,743,535
|
|
Hodgins
|
April 28, 1998
|
Compression piston ring seal
Abstract
A sealing system for the compression ring (5) of a piston (1) of an
internal combustion engine comprises placing an elastomeric material seal
ring (15) behind the compression ring (5) to provide sealing to improve
compression ratio and prevent loss of oil. The seal ring may be an O-ring
of a neoprene/silicon blend elastomeric material of circular, U-shaped,
oval, square, rectangular or trapezoidal shape, and may be hollow or
solid. The seal ring may have a cross-sectional diameter of from 50% to
100% of the thickness of the compression ring (5) behind which it fits.
| Inventors:
|
Hodgins; Sydney Gilbert (Port Augusta, AU)
|
| Assignee:
|
Auto-Motive Improvements Pty Ltd. (Fullarton, AU)
|
| Appl. No.:
|
718437 |
| Filed:
|
September 26, 1996 |
| PCT Filed:
|
August 15, 1994
|
| PCT NO:
|
PCT/AU94/00473
|
| 371 Date:
|
September 26, 1996
|
| 102(e) Date:
|
September 26, 1996
|
| PCT PUB.NO.:
|
WO95/27133 |
| PCT PUB. Date:
|
October 12, 1995 |
Foreign Application Priority Data
| Current U.S. Class: |
277/434 |
| Intern'l Class: |
F16J 009/06 |
| Field of Search: |
277/165,216
525/104,100
|
References Cited
U.S. Patent Documents
| 2940803 | Jun., 1960 | Phillips | 277/216.
|
| 3525530 | Aug., 1970 | Bauer et al. | 277/165.
|
| 3727927 | Apr., 1973 | Packard | 277/216.
|
| 3751047 | Aug., 1973 | McGee | 277/165.
|
| 3851889 | Dec., 1974 | Nisper | 277/214.
|
| 3862480 | Jan., 1975 | Packard et al. | 29/156.
|
| 3919448 | Nov., 1975 | Dufresne | 428/157.
|
| 4569868 | Feb., 1986 | De Blauwe et al. | 428/35.
|
| 5197746 | Mar., 1993 | Rehfeld | 277/144.
|
| Foreign Patent Documents |
| 3606886 | Sep., 1987 | DE | 277/165.
|
Primary Examiner: Cummings; Scott
Attorney, Agent or Firm: Baker, Maxham, Jester & Meador
Claims
I claim:
1. A piston having a diameter and of a type including a compression ring
groove having an axial width and a radial depth, a compression ring having
an axial thickness about equal to the axial width of the compression ring
groove and being mounted in the compression ring groove, the compression
ring being of a cross-sectional shape having an inner surface and upper
and lower faces and a recess between its inner surface and its lower face,
a sealing means in the compression ring groove behind the compression ring
wherein the sealing means is an O-ring of a heat resistant elastomeric
material, of a cross-sectional shape selected from the group consisting of
circular and oval, and wherein the O-ring has an axial dimension of
between about 50% and 100% of the axial thickness of the compression ring,
said O-ring being configured to at least partially deform into the recess
during the compression stroke of the piston.
2. The piston recited in claim 1, wherein the O-ring is a blend of neoprene
and silicone rubbers.
3. The piston recited in claim 1, wherein the O-ring has an outside
diameter substantially equal to the diameter of the piston.
4. A piston having a diameter and of a type including a compression ring
groove having an axial width and a radial depth, a compression ring in the
compression ring groove, the compression ring being of a cross-sectional
shape having an inner surface and upper and lower faces and an angular
bevel between its inner surface and its lower face, a sealing means in the
compression ring groove behind the compression ring wherein the sealing
means is an O-ring of a heat resistant elastomeric material which is a
blend of neoprene and silicone rubbers, of a cross-sectional shape
selected from the group consisting of circular and oval, and wherein the
O-ring has an axial dimension of between about 50% and 100% of the axial
thickness of the compression ring and an outside diameter substantially
equal to the diameter of the piston.
Description
TECHNICAL FIELD
This invention relates to efficient sealing in automobile engines and
particularly to sealing of engine cylinders in internal combustion engines
to prevent loss of oil and to improve compression ratio.
BACKGROUND OF THE INVENTION
Pistons in internal combustion engines usually include three sealing rings
around their periphery which engage with the cylindrical inner surface of
an engine cylinder. These three sealing rings each are designed to perform
a specific function. An uppermost of the seals provides a compression ring
which is designed to seal during an upstroke of a piston to provide
compression of the combustion gasses within the cylinder. The middle of
the three rings is designed as an oil scraping ring to prevent oil from
being carried up into the piston chamber and being burnt. A third ring is
actually an oil spreader ring or oil control ring to provide an even film
of lubricant on the piston wall. Some engines, particularly large engines,
may have two or three compression rings per piston.
As wear in an engine occurs, however, these various rings do not carry out
their function efficiently and an engine can burn more oil and have
insufficient compression to provide inefficient and incomplete combustion
of fuels. This can result in a build up of carbon deposit in the various
rings and grooves which prevent the proper action of the piston rings with
subsequent problems to efficiency of the engine and the burning of engine
oil.
The compression ring in particular carries out a most important function
but as wear occurs the ring can twist in its ring groove on both the up
and down strokes of a piston and can tend to score the cylinder wall and
also cause wear in the ring groove. This in turn causes further problems
with sealing of the compression ring.
OBJECTS OF THE INVENTION
It is the object of this invention to provide an arrangement and a method
to improve the efficiency of sealing and action of the compression ring of
an internal combustion engine.
An alternative object is to provide the public with at least a useful
alternative piston ring system.
SUMMARY OF THE INVENTION
In one form therefore although this may not necessarily be the only of
broadest form the invention is said to reside in a piston including a
compression ring groove, a compression ring in the compression ring groove
and a sealing means in the compression ring groove behind the compression
ring.
Preferably the sealing means is a seal ring of an elastomeric material. The
seal ring of elastomeric material may be an O ring which has a
cross-section shape selected from U-shaped, circular, oval, square,
rectangular or trapezoidal and maybe hollow or solid.
Preferably the seal ring of elastomeric material is made from a heat
resistant and oil resistant elastomeric material. Such a material may be a
blend of neoprene and silicone rubbers.
In an alternative form the invention may be said to reside in a method of
improving the compression ratio of an internal combustion engine including
the step of removing the piston ring from the uppermost ring slot of each
piston of the engine, inserting an O-ring into the uppermost piston ring
slot and replacing the piston ring.
In a further form the invention may be said to reside in a sealing means to
effect an improved seal of a compression ring of a piston of an internal
combustion engine comprising an elastomeric material seal ring adapted to
be fitted into a compression ring groove of the piston to engage with the
rear or inner surface of the compression ring and an innermost peripheral
surface of the compression ring groove.
Preferably the seal ring also engages a lower side surface of the
compression ring groove.
It will be seen that by the various forms of the invention there is
provided a seal ring behind the compression ring which is comprised of an
elastomeric material such that a steady and even force is provided onto
the rear of the compression ring to hold it evenly against the wall of the
cylinder during the up and downstroke thereby preventing uneven wear and
damage to the cylinder or to the piston ring.
Although the theory behind the successful operation of the seal ring of the
present invention is not clear it may be that the action of the sealing
ring during the compression stroke of the engine is one in which pressure
of gasses through the upper part of the ring slot exerts a force onto the
upper surface of the elastomeric seal ring thereby deforming the seat ring
to cause a seal between the compression ring, the rear or inner surface of
the compression ring groove and the lower surface of the compression ring
groove.
Without the seal ring arrangement of the present invention a small
percentage of compressed gas can pass the first piston ring but with the
seal ring of the present invention escape of such gasses is prevented.
Hence, in an engine which would normally have a compression ratio of
perhaps 160 to 175 pounds per square inch, the compression ratio can be
increased to 220 to 230 pounds per square inch. Such an increase in
compression ratio can increase engine efficiency and may allow for use of
cheaper fuels.
The seal ring system of the present invention may be used with engines
powered with diesel fuel, petrol, LPG or LNG or any other suitable blend
of fuel such as blends with methanol or alcohol.
In the case of a circular cross-section O-ring the diameter of the cross
section of the O-ring is preferably 50 to 100% of the width or thickness
of the piston ring. Hence for a 2 mm wide piston ring the diameter of the
cross-section of the O-ring may be 1.5 mm.
The overall diameter of the O-ring may be such that the outer diameter of
the O-ring may be the same as the outer diameter of the piston into which
the O-ring is fitted. Hence when the O-ring is actually placed into a
compression ring groove the O-ring is not in tension and may be slightly
in compression when a compression ring is placed around it. This will
assist with providing an outward force onto the rear or inner surface of
the compression ring to provide even travel of the front surface of the
compression ring on the cylinder wall.
A particular problem with gas powered engines is that the cleanliness of
the fuels tends to cause glazing on the cylinder walls. This will cause
blow-by of combustion gasses past the compression ring and this tends to
restrict the amount of oil that can be deposited on the cylinder walls. By
the use of the sealing system of the present invention, this blow-by will
be prevented and the oil control ring and the oil scraper ring can deposit
a suitable film of oil onto the cylinder wall thereby preventing glazing.
With petrol and diesel engines as well as with gas engines the fact that
there is no blow-by of combustion gasses past the compression ring will
mean that a certain amount of oil can be deposited on the surface of the
piston and some of this oil can be carried up into the underside of the
compression ring and carried into the compression ring groove to provide
cooling and lubrication for the O-ring.
The method and device of the present invention may be used with a new
engine or to improve the efficiency of a worn engine.
Where an engine has pistons with more than one compression ring then the
application of the present invention may be to only one of the compression
ring grooves.
This then generally describes the invention but to assist with
understanding of the invention reference will now be made to the
accompanying drawings which show preferred embodiments of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a part sectional view of a cylinder of an internal combustion
engine with a piston in it incorporating the seal ring of the present
invention,
FIG. 2 shows a detailed view of a compression ring of a piston of an
internal combustion engineshown in FIG. 1,
FIG. 3 shows a schematic view of the action of a compression ring and seal
ring during actual operation.
FIG. 4 shows a range of possible cross-sectional shapes of a seal ring
according to the present invention,
FIG. 5 shows an alternative embodiment of seal ring and compression ring of
an internal combustion engine, and
FIG. 6 shows a still further embodiment of a compression ring and a seal
ring of the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
Now looking more closely at the embodiment shown in FIG. 1 to FIG. 3 it
will be seen that the internal combustion engine has a piston 1 travelling
in a cylinder 2 defined by a cylinder wall 8 and a cylinder head 4. The
piston 1 has three sealing rings. An uppermost sealing ring is a
compression ring 5 in a compression ring groove 6, the ring having a
thickness about equal to the axial width of the groove. The middle sealing
ring is an oil scraper ring 7 in an oil scraper ring groove 8. The lowest
ring is an oil control ring assembly 9 in an oil control ring groove 10.
The oil control ring groove 10 includes an oil supply port 11 which
supplies oil from the interior of the piston to the oil control ring.
The compression area of the piston 1 is shown in more detail in FIG. 2 and
FIG. 3 and it will be particularly seen that a seal ring 15 has the form
of a circular cross section O-ring and is placed behind (radially inward)
the compression ring 5. It will be noted that at the relaxed position the
O-ring 15 is not under significant compression.
As can be seen in FIG. 3 when the piston 1 is in a compression stroke and
moving upwards compressed gasses are forced down between the cylinder wall
3 and the piston 1 and enter the very narrow gap at the top of the ring
groove 6 above the compression ring 5 and enter the rear of the
compression ring groove 6 behind the compression ring 5. If the seal ring
15 was not present then a certain amount of the combustion gasses could
pass under the lower face or surface of the compression ring 5 and cause
blow-by. It will be noted, however, that the force of the compressed
gasses caused deformation of the O-ring which distorts it so that it seals
against the rear (inner) surface of the compression ring 5 and the rear
surface 16 of the ring groove 6 and also onto the lower surface 17 of the
ring groove. By this means a sufficient seal is provided while at the same
time maintaining an even forward force on the compression ring 5 against
the cylinder wall 3 so that it travels up and down smoothly.
FIG. 4 shows several embodiments of possible cross-sections of O-rings
which may be used as the seal rings of the present invention.
FIG. 4(a) shows a U-shaped cross-section O-ring which will be useful to
provide sealing against the rear surface of the ring groove, the lower
surface of the ring groove and the rear of the piston ring. FIG. 4(b)
shows a square section seal ring with a hollow centre. FIG. 4(c) shows a
trapezoidal cross-section seal ring. FIG. 4(d) shows an oval cross-section
ring. FIG. 4(e) shows a U section seal ring similar to the seal ring shown
in FIG. 4(a). FIG. 4(f) shows a semi-circular or semi-elliptical
cross-section O-ring. Such a shape of O-ring may be used with the flat
surface facing inwards, outwards, up or down.
FIG. 5 shows an alternative embodiment of a seal ring and compression ring.
In this embodiment the compression ring 20 includes a semi-circular recess
at the rear bottom of the compression ring and an oval cross-section seal
ring 21 is placed behind the compression ring in the ring groove 22 of the
piston 23 to provide a seal.
The embodiment shown in FIG. 6 shows a piston 30 with a compression ring
groove 31 with a compression ring 32 in the groove 31 which has a recess
into its back surface into which is fitted a rectangular cross section
O-ring 33. This form of O-ring provides a resilient force to hold the
compression ring 32 evenly against the cylinder wall and provides sealing
to prevent combustion and compressed gasses from passing behind the piston
ring.
Throughout this specification and the claims that follow unless the context
requires otherwise, the words `comprise` and `include` and variations such
as `comprising` and `including` will be understood to imply the inclusion
of a stated integer or group of integers but not the exclusion of any
other integer or group of integers.
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